He was born in Saint-Brieuc, Côtes-d'Armor, France. He committed suicide at age 35 in Paris.

Short-lived Patrick Dewaere was one of the most promising and popular French actors of the '70s. In 1968, he joined Café de la Gare, the troupe of performers which also included such future stars as Gérard Depardieu and Miou-Miou. After initially appearing under the pseudonym Patrick Morin, he finally opted for Dewaere, which was his grandmother's maiden name. Onscreen from 1971 in various bit parts, Dewaere made the breakthrough with his first major role in Bertrand Blier's anarchic comedy Les Valseuses (1974) where he and Gerard Depardieu starred as two young delinquents. The actor would team up again with Depardieu in Blier's Oscar-winning comedy Preparez Vos Mouchoirs (1978). Despite Dewaere's obvious talent for comedy, he was often successfully cast as a fragile, neurotic individual. Shortly after the release of Paradis Pour Tous (1982), the black comedy where his character committed suicide, the actor shot himself in a hotel room. The Patrick Dewaere Award was established in France in 1983. The actor was the subject of the French documentary Patrick Dewaere, which was shown at the Cannes Film Festival in 1992.